Retail and other business establishments that serve a large number of customers generally have a problem obtaining information about the number of persons visiting their premises. However, information about the number of visitors currently visiting the premises and distribution of the visitors in time is extremely valuable not only for arranging enough staff to serve customers where it is needed but also generally in planning the business.
It is known in the art to arrange sensors at the entrances to the premises for counting the number of persons that have gone in and out. A sensor may comprise a photoelectric cell and a counter both integrated in the same case. Every time when a person passing by cuts the beam of the photocell, the reading of the counter is increased.
Sensors based on photoelectric cell technology may yield erroneous figures. This is due the fact that two or more persons moving side-by-side may increase the reading of a sensor only by one. Therefore, the sensor gives readings that are too low. Especially with high visitor flows, the error accumulates along with the growing flow of people. Counting accuracy can be improved by installing several photocells in parallel but this increases costs.
More accurate counting results are achieved by mounting a thermal imaging sensor on the ceiling above a passageway. The sensor applies thermal imaging technology that uses infrared recognition to gather information about the size, placement, direction and stopping of an object beneath. Relying on these parameters the operator can decide which objects are accepted to increase the reading of the counter. The thermal imaging sensor can count visitors along the passageway even when several persons walk next to each other. In this way high accuracy can be achieved which is not dependent on the level of light or color changes. A typical recognition field of the thermal imaging sensor is about 4.5 m×4.5 m. By chaining several thermal-imaging sensors it is possible to monitor very wide passages.
Further, a sensor of radar type is also known. It detects any form of movement in a room and can even penetrate some construction materials. Also a mat sensitive to dynamic force may be used as a sensor especially in places where only one person in turn crosses the mat.
It is also known to connect outputs from a plurality of counters to a visitor data processing computer that receives visitor data flow. The computer includes a specific software program that is adapted to process the visitor data and produce various types of reports. Thus, a report may tell the number of visitors per hour, day, week, and year in the form of figures and/or graphic charts, for example.
However, instead of connecting the counters directly to the computer its is advantageous to connect them to a data-recording device comprising a buffer memory for temporarily storing incoming data received from the counters, a memory for persistently storing visitor data, and an data transfer interface for communicating with the computer. In addition, the data-recording device includes a clock for giving accurate time for time stamps that are attached to pieces of data. Especially when several sites in an establishment are provided with several visitor counters it is practical to wire the counters of a site to a data-recording device installed at that site. In order to avoid additional wiring and making installation easy and rapid, it might be advantageous to connect the data-recording devices wirelessly to the visitor data processing computer. Today many establishments like stores are provided with a WLAN-network wherein that network may be used to carry communication between the data-recording devices and the visitor data processing computer.
Hence, each counter is wired to its own terminal in the data-recording device that accordingly knows the origin, i.e. the counter, of each incoming data flow. Therefore the data-recoding device is able to attach a counter identifier and the time stamp for each dataflow.
For example, a merchant is interested in getting information about the number of visitors per hour. There are several entrances to and exits from his store, each entrance and exit being equipped with at least one photocell visitor counter. Now, the data-recoding device is instructed to store readings from the counters in the buffer memory and also put a time stamp indicating beginning of each record. After one hour's buffering period has lapsed, the data-recoding device inserts the records from the buffer memory into the non-volatile memory. Each record is provided with a time stamp indicating the end of the buffering period and also with the identifier of the counter that generated the data of said record. As a result, the non-volatile memory contains a data record for each counter, the record comprising time stamps indicating the starting and ending moments of the data collecting period, the counted number of visitors during the period, and the identifier of the counter. At the same time incoming data for the next period are collected in the buffer. In this manner the non-volatile memory contains an increasing amount of records, from which the records of a certain counter and their chronological order are easily extractable. After the store has been closed for that day, all the records are transmitted to the visitor data processing computer that processed the records and generates various reports and graphic charts.
Most often the above-described visitor counting system is local, i.e. the system is installed in an establishment and operated and managed locally. However, by combining several local systems it is possible to build a large system that is managed and operated remotely.
FIG. 1 illustrates such a system. In establishment 10, which may be a large store, there are several sensors counting visitors passing by. Thermal image thermal imaging sensor 101 located at the ceiling of a wide entrance point counts the number of people below. Photoelectric sensor 102 fitted in the wall of a corridor counts the number of people passing by whereas a sensor using a dynamic force-sensitive matt 104 located at the floor of a lift counts the number of lift passengers. The output of each sensor is connected to a respective terminal of data recording device 103. In this example there are three input terminals but the data-recording device may have several input terminals for connecting additional sensors when needed. Every time when a sensitive element of the sensor detects a visitor within its influencing area, it produces a pulse that increments the counter. The pulse is also transmitted to the terminal of the data-recording device wherein a counter in the device is also incremented and the current counter value is stored in a buffer Thus, the visitor flows passing by sensors 101, 102 and 104 cause the counter value in the respective buffer to be increased. Periodically the values in the buffer are shifted to appropriate fields of records to be formed.
FIG. 2 depicts fields of the record. The record contains time stamp field 21 for storing date and time of the starting instant of the counting period, another time stamp field 22 for storing date and time of the ending instant of the counting period, a field 23 for storing the identifier of a sensor, a field 24 for storing the counter value shifted from the buffer, and one or more fields 25 for additional data. These kinds of records are generated periodically for each sensor connected to the data-recording device.
In other words, in pre-set time periods the counter value in the buffer is shifted to the non-volatile memory of the data-recording device. The time period may be one hour, for example. At the same moment the buffer is also cleared for receiving counter values of the next period. Hence, upon the lapse of the time period the counter value is shifted to counter value field 24 of the record to be formed. The time stamp indicating the starting instant of the period has been inserted in the field 21 previously as well as the individual identifier of the sensor in question into the field 23. The current time stamp is also inserted into the second time stamp field 22 indicating the ending instant of the period.
Referring back to FIG. 1, in another establishment 11, that may be a multi-story shop, there are tow data-recording devices 105 and 106. Thermal imaging sensor 107 is counting the number of people below whereas photoelectric sensors 108 and 109 are counting the number of people passing by along a corridor or via a gate, for example. These sensors are located physically near enough each other so that the sensors are wired to common data-recording device 105. Other sensors 110 and 111 are wired to another data-recording device 106. Both data-recording devices generate periodically above-explained records and store the records in a non-volatile memory.
Instead of processing gathered counter values, i.e. records, locally in a dedicated computer, the records are processed centralized in a remote visitor data processing unit 120. Therefore, in response to a request received from the visitor data processing unit, data-recording devices 103 and 105 transmit the collected records via a transmission network to the visitor data processing unit. The transmission network may be a wired network 115 like PSTN or a computer network as the Internet, or a wireless network 116 as any cellular network. Corresponding telecommunication facility for communicating with the visitor data processing unit is installed in the data-recording devices. For example, the data-recording device 105 includes a built-in cellular phone, which makes installation of the visitor counting system in an establishment reasonable easy and fast.
The visitor data processing unit takes a connection with the data-recording devices automatically. Advantageously the connections are set up in the nighttime when the establishments are closed and the records of the whole previous day are available in the data-recording devices. During the connection the records are transmitted to the visitor data processing unit and cleared from the memory. In addition, the visitor data processing unit updates the clocks of the data-recording devices so that their date and time are always accurate. If the first connection attempt fails subsequent attempts are made until all records are transmitted. The records are stored in a database as a raw data.
After the visitor data processing unit 120 has fetched all the data gathered by the data-recording devices in the establishments 10 and 11, it starts to process the raw data. Processing is made relating to each establishment and to each particular sensor in the establishment. This is possible because the records of a particular sensor are easily extractable from the raw data based on the sensor identifier. Henceforward the flow of records originating from a sensor is called as “sensor channel”.
Basically the processing is straightforward; the records of the desired sensor are extracted from the raw data and then the records are arranged in chronological order using the time stamps. Thereafter visitor statistics in the form of various graphs and figures depicting the amounts of visitors per time period (e.g. per hour) are formed. By combining statistics based on the sensor channels originating form the same establishment a plurality of summary reports are produced that the administrator of the establishment in question can utilize in business.
US 2004/238628 A1 discloses a people counting system comprising a plurality of “people counting data collection units”, which are termed briefly “units”. The units include appropriate hardware and/or software to gather, store, analyze, and present the people counting statistical data. A unit can advertise its presence to other units of the people counting system so that other units will be aware of the existence of that unit. A unit may be configured to advertise its presence to other units at certain time intervals by sending messages. Once each unit is aware of the other units, each unit maintains or has access to a list of all the advertised units. In addition to maintaining the list of advertised units, a unit can automatically, or via instruction from a user, access people counting statistical data from any unit of the system.
A drawback of the today's centralized visitor counting systems is that they do not pay attention to the validity of data. Namely, data or a piece of data may be incorrect due to incorrectly functioning sensors. In other words, if a sensor that previously has functioned properly for some reason starts to count visitors erroneously, said erroneous data is not detected but they distort the reports. Moreover, the faulty sensor can produce erroneous data for a long time until it will be, perhaps, discovered in a maintenance operation. In addition, data or a piece of data may also be incorrect due to a data transmission failure or a drift in time and date settings in the data-recording device.
Another drawback relates to missing data. When some records are totally missing in the raw data it results in empty figures in reports. For example, if the record of a sensor that should indicate the number of visitors passed by the main entrance of a store between 2 and 3 p.m. is missing, the report tells that no visitors have come in during that time. In fact, quite often the raw data contain missing and invalid records, which decreases reliability of the reports.